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Hello- I will soon be digging the footers for our new home here in St, Simons Island, Ga. I am a DIY’fer with moderate experience. The design is called the Gulf Coast Cottage (Southern Living plans), and is a 2500 sq. ft. design on one level, with a wrap around porch and a big ol hipped roof.The house sits up on concrete piers that are tied into individual footings. due to the nature of the soil here {very sandy,porous, and with occasional marsh muck} I am of course concerned about settling. Our lot is fairly low, about 8 ft above MSL. We had the existing palmettos ripped out back in June and added back many loads of fill, which was compacted by the dozers as it was dumped (June,2000}My guess is they added 4 ft. above the undisturbed earth.Our plan is to have the garage underneath the house. I have a few questions- – IF there is a minimum of organic stuff in the fill, and with average rainfall, how important is it to wait and how long should you wait before pouring foundation? Why is it important to pour the slab for the garage around the piers instead of pouring the footers for the piers and the slab all in the ame pour? Id like to hear any other comments or experiences any of yall have had with similiar situations. I do plan to consult with an engineer before proceding but I feel I would be better prepared after hearing many other opinions. I have lurked around this forum for a couple of years now, and really have enjoyed it. Thank you all in advance. I have several other questions about this house to be posted on later threads. Thanks again.
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Charles,
Notwithstanding of all the good advice this forum has provided in the short time I've been posting here, the people you need to be talking to are at the local planning and building department. I live and build on the west coast of Florida. What is code here may not be on the Georgia coast. Our local building department would require some serious compaction backed up by tests to allow a foundation system on that much fill. I say system because we must have a continuous footer, the exception being pile driven pillars. I don't know about your location. Coastal construction present some unique building problems, each addressed differently by every building department. What's acceptable around Sarasota won't pass in the Keys, and in spite of what my Conch friends might think, it's the same state. Good luck and keep us posted.
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Hi Charles,
On the issue of the slab being poured around the footings, you want the slab to be a separate, floating unit. That way when the footings settle 1 or 2 inches with the weight of the house on them they won't bust up the slab in the process.
Imagine laying a piece of 8" x 10" cardboard on some sand, about an inch deep. Place nine 1" dowels standing on end on the cardboard, one at each corner, one at each side, and one in the middle. Now start stacking books on top of the dowels and watch as the cardboard "slab" distorts.
Now imagin if you cut holes in the cardboard so the dowels can pass through. I think you get the idea.
*Thanks for the quick respomses- Ted- Good analogy. I was thinking the slab would be stronger, I guess, and maybe spread the load around some. Also I am concerned with moisture migration- wicking up the piers and evaporating inside the garage/ shop area. Although it is required by FEMA to be vented, or partially open to allow a storm surge to pass under the structure without wrecking it (theoretically), It seems it would be much easier to seal a complete slab with poly than to try to seal the bases of all those piers! comments?
*Gee Charles, you got me there. I think the joint between the footings and the slab are supposed to have an expansion joint - a 34" thick strip of asfalt impregnated material. I don't know if this prevents a "wicking" effect or what happens to a membrane under the slab and footings when they settle differently. I imagine the membrane would break at that point.
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Hello- I will soon be digging the footers for our new home here in St, Simons Island, Ga. I am a DIY'fer with moderate experience. The design is called the Gulf Coast Cottage (Southern Living plans), and is a 2500 sq. ft. design on one level, with a wrap around porch and a big ol hipped roof.The house sits up on concrete piers that are tied into individual footings. due to the nature of the soil here {very sandy,porous, and with occasional marsh muck} I am of course concerned about settling. Our lot is fairly low, about 8 ft above MSL. We had the existing palmettos ripped out back in June and added back many loads of fill, which was compacted by the dozers as it was dumped (June,2000}My guess is they added 4 ft. above the undisturbed earth.Our plan is to have the garage underneath the house. I have a few questions- - IF there is a minimum of organic stuff in the fill, and with average rainfall, how important is it to wait and how long should you wait before pouring foundation? Why is it important to pour the slab for the garage around the piers instead of pouring the footers for the piers and the slab all in the ame pour? Id like to hear any other comments or experiences any of yall have had with similiar situations. I do plan to consult with an engineer before proceding but I feel I would be better prepared after hearing many other opinions. I have lurked around this forum for a couple of years now, and really have enjoyed it. Thank you all in advance. I have several other questions about this house to be posted on later threads. Thanks again.